Serial induction of mutations by ethylnitrosourea in PC12 cells: a new model for a phenotypical characterization of the neurotoxic response to 6-hydroxydopamine

TM9SF1 offers utility as an efficient predictor of clinical severity and mortality among acute respiratory distress syndrome patients

Introduction

Acute respiratory distress syndrome (ARDS) is a major cause of death among critically ill patients in intensive care settings, underscoring the need to identify biomarkers capable of predicting ARDS patient clinical status and prognosis at an early time point. This study specifically sought to explore the utility and clinical relevance of TM9SF1 as a biomarker for the early prediction of disease severity and prognostic outcomes in patients with ARDS.

Methods

This study enrolled 123 patients with severe ARDS and 116 patients with non-severe ARDS for whom follow-up information was available. The mRNA levels of TM9SF1 and cytokines in peripheral blood mononuclear cells from these patients were evaluated by qPCR. The predictive performance of TM9SF1 and other clinical indicators was evaluated using received operating characteristic (ROC) curves. A predictive nomogram was developed based on TM9SF1 expression and evaluated for its ability in the early prediction of severe disease and mortality in patients with ARDS.

Results

TM9SF1 mRNA expression was found to be significantly increased in patients with severe ARDS relative to those with non-severe disease or healthy controls. ARDS severity increased in correspondence with the level of TM9SF1 expression (odds ratio [OR] = 2.43, 95% confidence interval [CI] = 2.15-3.72, P = 0.005), and high TM9SF1 levels were associated with a greater risk of mortality (hazard ratio [HR] = 2.27, 95% CI = 2.20-4.39, P = 0.001). ROC curves demonstrated that relative to other clinical indicators, TM9SF1 offered superior performance in the prediction of ARDS severity and mortality. A novel nomogram incorporating TM9SF1 expression together with age, D-dimer levels, and C-reactive protein (CRP) levels was developed and was used to predict ARDS severity (AUC = 0.887, 95% CI = 0.715-0.943). A separate model incorporating TM9SF1 expression, age, neutrophil-lymphocyte ratio (NLR), and D-dimer levels (C-index = 0.890, 95% CI = 0.627-0.957) was also developed for predicting mortality.

Conclusion

Increases in ARDS severity and patient mortality were observed with rising levels of TM9SF1 expression. TM9SF1 may thus offer utility as a novel biomarker for the early prediction of ARDS patient disease status and clinical outcomes.

Acute effects of 6-hydroxydopamine on dopaminergic neurons of the rat substantia nigra pars compacta in vitro

6-Hydroxydopamine (6-OHDA) is a neurotoxin which has been implicated in the degeneration of dopaminergic neurons of the substantia nigra pars compacta (SNc) in Parkinson's disease (PD), and is frequently used to produce animal models of the disease. The aim of our study, conducted on midbrain slices obtained from young Wistar rats, was to determine the little known acute effects of this toxin (0.2-2.0 mM; 10-20 min exposure; 34 degrees C) on electrophysiological properties, intracellular Ca2+ levels and dendritic morphology of SNc neurons. Four experimental approaches were used: extracellular recording of firing frequency, whole-cell patch-clamping, ratiometric fura-2 imaging, and cell labeling with lucifer yellow (LY) or dextran-rhodamine. Extracellular recording revealed a concentration-dependent decrease in the tonic, pacemaker-like firing. In whole-cell recordings in voltage-clamp (V(hold) -60 mV), smaller doses (0.2-0.5 mM) induced an outward current (or cell membrane hyperpolarization in current-clamp), which could in some cells be reversed with tolbutamide (blocker of ATP-dependent K+ channels). A higher dose (1.0-2.0 mM) caused rapid reductions of cell membrane capacitance and membrane resistance. Toxin exposure gradually increased the intracellular Ca2+ level, which did not subsequently return to control. The increase in Ca2+ signal was not prevented by depletion of intracellular Ca2+ stores with thapsigargin (10 microM) or cyclopiazonic acid (30 microM), nor by removing extracellular Ca2+. Cell membrane current and Ca2+ responses were not prevented by blocking dopamine transporter (DAT). Cells loaded with LY or dextran-rhodamine showed signs of damage (cell membrane blebbing) in dendrites following toxin exposure (1 mM; 10-20 min). These results demonstrate that the oxidative and metabolic stress induced in SNc neurons by 6-OHDA results in rapid dose-dependent changes of cell membrane properties with morphological evidence of dendritic damage, as well as in disturbance of intracellular Ca2+ homeostasis.